1. Field of the Invention
The present invention relates to a winder.
2. History of the Related Art
Such winders are known and wind a usually freshly produced, endless, flexible material web onto a winding core until a reel of predetermined size is wound. The material web is then cut and the finished reel is preferably flyingly replaced by a new winding core, so that a new reel can be produced without delay and as far as possible without material loss.
The flexible material web is frequently a plastic film but can also consist of other materials. In particular, plastic films are produced in an extraordinary multiplicity of compositions and accordingly with various properties, which then also influence the winding behavior and accordingly must be taken into account during winding. Likewise, the respective production speed as well as the number of reels to be produced in a production run are parameters which must be taken into account for satisfactory-quality production at the same time as reasonable costs.
Typical processing speeds range from 2 to 1000 m/min, while the finished winding bales can have a diameter of 50 to 2000 mm or a width of 10 to 4000 mm. The thickness can range from a few micrometers as far as the millimeter range. Depending on the requirement, the production varies between the manufacture of only a few dissimilar winding bales as far as the mass production of identical winding bales.
The winding itself is effected, depending on the material properties of the flexible material web, for example, as contact winding in which a contact roller maintains contact with the forming bale and thus applies a pressing force thereon. Accordingly, the winding is also effect as gap winding, i.e. without a contact roller touching the winding bale during the winding. Apart from a few exceptions, the flexible material web is guided in front of the winding bale around a contact roller, which helps to smooth the material web before winding, especially if the diameter is large.
The pressing force, along with the web tension, is a critical parameter for the quality of the winding bale and must be adjusted as optimally as possible with regard to the (numerous, see above) material properties. For example, the pressing force should be selected correctly according to the friction of the material web or film layers among one another, likewise after adding lubrication to the formulation of the material web. Frequently, the pressing force must be varied during winding, e.g. depending on the diameter of the reel which is building up.
The web tension of the material web looping around the contact roller can now, depending on the geometry of the winder or the suspension of the contact roller, result in a force component, which is added to the pressing force already produced. In the present case, it is assumed that the web tension has no influence in this regard or is appropriately taken into account by the person skilled in the art when designing the winding, so that it is superfluous to take into account feasible perturbations of the pressing force due to the web tension in the description of the present invention.
The optimal pressing force, always in regard to a good-quality reel, is dependent on the material properties such as, for example, friction, stickiness, lubricant content, and not least air ingress between the layers of the material web to be wound, accordingly also on the progress (diameter) of the forming reel. In other words, it is the formulation of the material which determines its winding properties; frequently, the formulation is an operating secret of the respective manufacturer. From the many-faceted nature of the influences on the winding properties of the material to be wound, it also follows that merely a small variation in the pressing pressure can change the quality of the winding.
Optimal pressing pressure therefore also means constant pressing pressure, i.e. without fluctuations, due to which the quality of the reel can be negatively influenced.
An important example for the quality of the reel is the defective formation of the roll level (end faces of the reel), i.e. layers displaced with respect to one another in the reel, which are visible at the sides of the reel, similar to an annual ring in a tree trunk. At the sides of the winding bales, even slightly protruding edges of the material web or the film tend to fold over, at the latest during unwinding, with the result that cracks can then form at the edges of the material web, which result in the unwound film being rejected. Thus, for example, for certain packaging tasks, the plastic film to be unwound is multiply stretched during the unwinding. The smallest winding defects then lead to tearing of the film, which results in an interruption in production with corresponding damage.
In other words, winding defects are tabooed, but are a frequent problem which is not least caused by nonoptimal pressing pressure.
Overall, it is found that a winder must generally be configured as a universal winder, which can be operated with tolerable retrofitting times for changing production. This includes the fact that contact winding or gap winding can be carried out, furthermore flying change of the reel, and the winding in the range of the aforesaid various parameters.
The numerous designs known today can be summarized in three groups: (i) static (i.e. rigid) mounting of the winding core bearing and dynamic (movable) mounting of the contact drum, see DE 33 08 059, where in the case of contact winding, the advance of the contact drum is regulated as a function of the pressing force, (ii) dynamic mounting of the winding core bearing and static mounting of the contact drum, see DE 2 037 979, where the advance of the winding core carrier is also regulated as a function of the pressing force and (iii) dynamic mounting of the winding core bearing and contact roller, see EP 0 561 128, where the advantages of static and dynamic mounting particularly in regard to the protruding residual material (material loss) at the finished reel after the flying change should be combined.
Common to all three examples is the fact that the quality of the winding bale should be improved compared with the prior art.
Likewise it is the object of the present invention to provide a method for improved winding of a web of flexible material and a winder, which is suitable for gap and contact winding, and can be used universally, and which further improves the quality of the reel produced during contact winding.
Since the winder core is continuously displaced from the contact roller, completely uniform operation of the winder is achieved under ideal conditions, so that perturbing influences on the pressing force e.g. due to the inertial mass of the accelerated contact roller or the accelerated reel are avoided; this is with the advantage of a statically mounted contact roller with regard to the flying change of reel with little protruding residual material. Also absent, for example, are the pulsations in the generally hydraulic feed drive of contact roller and reel, which perturb the uniform pressing force, and which are difficult to avoid during stepwise or cyclic feeding of the reel or with a contact roller which moves to and from, and which have an unfavorable effect on the pressing pressure. Since the contact roller can be displaced from its desired position while maintaining the pressing force, errors occurring when the desired radius does not correspond to the actual radius remain further without consequence. In addition, pulsations or impacts caused by out-of-round reels are intercepted and damped, thus preventing high force peaks from building up in the pressing pressure. Finally, in addition to the improved contact winding, gap winding is furthermore also possible, likewise the usual requirements for a universal winder are satisfied as previously.